Changing glacier firn in Central Asia and its impact on glacier mass balance

The glaciated regions of Central Asia serve as water towers on a regional scale. For this dry region, the monitoring of glacier mass balance therefore provides valuable information for the estimation of water availability. In the 1990s, related to the end of the Soviet period, monitoring programmes were interrupted. On selected glaciers, the University of Fribourg and partner institutes could successfully reinitiate a mass balance monitoring. However, comparisons between in-situ measured mass balances and mass balance estimations based on remote sensing data reveal differences between the results both methods.

Major uncertainties in both approaches relate to the little explored changes in the firn cover, i.e. the porous and up to a few dozen meter thick near-surface layer of a glacier where snow densifies into glacier ice. Therefore, changes of meltwater percolation and retention in firn, and associated changes in firn density and/or temperature could possibly explain the differences between both methods.

Research aims/sciences questions:
(1) Establishing a century long accumulation time series of Abramov Glacier. 
(2) Design a firn model, calibrated with the measurements and applied to simulate and understand the processes in firn evolution.
(3) Apply the measurements and model to reconcile geodetic and in-situ glacier mass balances.

Methods/methodology of the project: Firn core drilling and analysis, legacy data, firn and glacier mass balance model, remote sensing

Study area: Glaciers in the Central Asian Tien Shan and Pamir mountains. Main focus on Abramov Glacier (Pamir-Alay).

• Illustrations
  

  Two examples of firn stratigraphy and density measured in 1974/75 deep snow pits on Abramov glacier

  source: Suslov and Krenke, 1980, stratigraphy is simplified compared to original source

  

  Abramov glacier

  Picture taken by Horst Machguth

• Publications
  • Barandun, M., Huss, M., Sold, L., Farinotti, D., Azisov, E., Salzmann, N., Usubaliev, R., Merkushkin, A., & Hoelzle, M. (2015). Re-analysis of seasonal mass balance at Abramov glacier 1968–2014. Journal of Glaciology, 61(230), 1103-1117.
  • Kronenberg, M., Barandun, M., Hoelzle, M., Huss, M., Farinotti, D., Azisov, E., ... & Kääb, A. (2016). Mass-balance econstruction for Glacier No. 354, Tien Shan, from 2003 to 2014. Annals of Glaciology, 57, 71.
  • Kenzhebaev, R., Barandun, M., Kronenberg, M., Yaning, C., Usubaliev, R., Hoelzle, M., (in review). Mass balance observation and reconstruction for Batysh Sook Glacier, Tian Shan, from 2004 to 2015. Cold Region Science and Technology.